Flexible mandrel



iii

Patented Feb. 25, 1930 UNITED STATES CHARLES F. WALP, OF BERWICK,PENNSYLVANA, ASSIGNORTO AMERCAN CAR AND FOUNDRY COMPANY, OF NEW YORK, N.Y., A CORPORATION OF NEW JERSEY FLEXIBLE MANDREL Application filed May2,

This invention relates generally to bending metal channels intopredetermined form, and has particular reference to a mandrel or formerto be inserted into a metallic channel to reinforce the latter fromwithin to prevent buckling or distortion thereof while it is being bent.

One object of the invention is to provide a flexible mandrel of the typeor character referred to, in which a substantially continuous smoothsurface is provided which will contact with the flanges and web of thechannel during the bending operation.

Another object of the invention is the provision of a flexible mandrelor former lor reinforcing or bracing the flanges and web of a channelwhile the latter is being bent into predetermined form, in which theelements thereof will contact with the oppositely arranged flanges ofthe channel at all times during the pressing operation, whereby toprevent distortion of the channel.

A. further object of the invention is the provision of a flexiblemandrel or former for reinforcing or bracing the flanges and web of achannel while the latter is subjected to the action of pressing orforming dies; which mandrel is formed of a plurality of separate andindependent relatively 'movable elements in the form of blocks normallyarranged in spaced series each comprising a plurality of said blocks.

A still further object of the invention is the provision of a mandrel'formed of spaced series of blocks which are relatively movable within achannel when the latter is subjected to the action of forming dies toposition said series adjacent each other and in conformity with theshape of the finished channel.

Still another objectvo'l the invention is the provision ot a flexiblemandrel of the character and for the purpose indicated, which is formedof a plurality of alternately arranged blocks loosely mounted on aflexible element whereby when a channel in which the mandrelis seated issubjected to the action of pressing or forming dies, said blocks moverelatively to eachother to conform to the shape of the iinished channelduring 192s. yserial no. 274,461.

pressing and sustain the channel against distortion.

Other objects and advantages oi'` this invention will be apparent fromthe following description, talren in conjunction with the accompanyingdrawings in which:

Fig. l is a view partly in front elevation and partly in verticalsection, showing the forming dies and the iiexible mandrel, thesectional portion of the figure being taken on the line l-l oi Fig. 2;

Fig. 2 is a sectional view on the line 2 2 of Fig. l;

Fig. 3 is a front elevation of a channel, before bending, showing theflexible mandrel positioned therein in section;

Fig. 4l is a sectional view of the channel and mandrel, taken on theline 4 4 of Fig. 3, the channel being shown in broken lines;

Fig. 5 is a side elevation of a bent channel showing the forming dies,and a modified form or lieXible mandrel in section; and

Fig. 6 is a side elevation of a channel before bending showing insection the mandrel shown in Fig. 5.

Referring now more particularly to the drawings in which similarcharacters of reference designate similar parts in the several views,the device oi the present invention is employed in association withforming dies comprising a stationary male die block A and a movablefemale die block B between which blocks A and B the channel C to be bentis placed.

The metal die block A is so formed as to provide a seat or base 2 and abacking plate l, the base 2 supporting a variable die 6 which is securedagainst displacement by suitable means s ch as the bolts 8 having theirends countersunk in the backing plate 4l and die 6, as clearly shown.The other variable die is shown at l0, and the same is secured to thefemale die bloclr B by bolts l2 or the like to move therewith to bendthe channel C into predetermined form. ln the instance shown, thearticle to be formed is a channel side piece or cross bar for a truckframe, and the formed channel comprises the main portion lil having theoli'set end portions 16 connected by the bends 17 and the variable diesare correspondingly shaped to effect this structure, as will beapparent.

In the forming of channels of the type shown, it is desirable toreinforce the same to prevent distortion vduring pressing, especially atthe bends 17 and the offset ends 16, and to effect this, I provideflexible mandrels of the type shown more clearly in Figs. 3 and 6 to beinserted in the ends of the channels.

Figs. 1 and l3, the same comprises stubstantially a plurality of blocks18 which are generally triangular or wedge shaped in form, each thereofhaving arcuate base and top portions 20 and 22 respectively and straightsides 24. As shown in the drawings, the blocks are alternately arranged,that is, the base 20 of one block is arranged adjacent the top 22 of thenext adjacent block and so on. The blocks are each provided withenlarged openings 23 therethrough by which they may be mounted on aflexible cable 26, the ends of which cable extend through sizing heads28 and 30 respectively. The sizing head 30 is provided with a recess inthe outer face thereof in which the inner end of a keeper 32 ispositioned. The keeper 32 is tubular being provided with an openingtherethrough which tapers from the outer end towards the inner end, andone end of the cable 26 extendsthrough the aperture as clearly shown;said end being swelled or enlarged at 34 in any suitable manner wherebyto prevent the cable being` withdrawn from the keeper. The

outer end of the keeper is externally threaded to secure an adjustingnut 36 adapted to bear against the outer face of the sizing head 30 foran obvious purpose, the sizing head being provided with a verticallyarranged inner face 38 against which the end block 18 bears.

Referring now to the sizing head 28, it can be seen in Fig. 3 that theinner face thereof is undercut at an acute angle to the vertical asshown at 40 to bear against the side of the adjacent endv block 18, andin this connection, it can be seen that when the flexible mandrel iskarranged in the channel before the latter is bent, the several blocks18 incline slightly at an acute angle to the vertical; the angle yofinclination being determined not only by the relative size of the baseand top portions of the blocks but also by the inner face of the sizinghead 80, and the shape of the inner face of the sizing head 28 isdetermined in accordance therewith. It will be apparent, therefore, thatthe angular inclination of the blocks with respect to the vertical planetherethrough is susceptible of many variations.

The outer face of the sizing head 28 is recessed as at 42 to provide aseat for a spring 44 which surrounds a socket46 through which and towhich the opposite end of the cable 26 extends and is secured. Thesocket is provided with a nut 48 forming a spring seat, as will beobvious.

Referring now to the mandrel shown in Referring now to the type ofmandrel shown in Figs. 5 and 6, it can be seen that the same comprisesseries of blocks indicated at D, E and F; D and F being end series and Ean intermediate series.

Each end series, in the instance shown herein, includes threealternately arranged blocks of triangular or wedge shaped form arrangedside by side, and the end series D and F are arranged at an angleinclined to the vertical plane through the blocks while the intermediateseries E is composed of four blocks arranged at substantially the sameangle of inclination but in a reverse direction, as clearly shown inFig. 6.

rIhe blocks forming the several series have been designated as 56, 58,60, 62, 64, 66, 68 and 70, 72 and 7 41 andall of them are mounted on aliexible cable 7 6 and retained there- 1on as hereinafter described. Theseveral series are retained in spaced relation by means of coil springs78 and 80 interposed between series D and E, and E and F respectively,and through them the cable 76 extends. In order to mount the blocks onthe cable, the blocks are provided with'openings and to permit thesprings 78 and 8O to be seated, the middle block of each end series isprovided with a recess 82 to define a spring seat 84, and the blocks 64and 66 are also provided with recesses to define spring seats 86 and 88respectively; springs 78 and 80 being positioned between series D and Eand E and F respectively by'means of the spring seats and in such amanner as to retain said series in spaced relation. The mandrel isadapted to flex as shown in Fig. 5 and therefore the adjacent blocks ofeach series are provided with enlarged openings 90 for an obviouspurpose. j

Sizing heads 92 are provided for retaining the several parts of themandrel in assembled relation, the heads having straight or verticalinner faces 94 against which the end blocks 56 and 74 bear, said headsbeing of such size as to fit within the channel and engage the flangesor chords thereof. Each head 92 is provided with a recess 96'which takesone end of a tubular socket 98 in which the ends of the cable aresecured, and adjusting nuts 100 engage the outer threaded ends of thesockets 98 and bind against the outer faces of the heads 92 for anobvious purpose.

In forming channels of the type shown in Fig. 5, it is desirable thatduring the pressing operation, the flanges or chords of the channel bereinforced at all points to prevent distortion, and the use of themandrels chords of the channel are always engaged during the pressingoperation for such an arrangement has been Vfound unnecessary, and infact a continuous engagement of all portions of the inner surfaces ofthe flanges is not desirable as it may strain'the metal of the flanges.l do mean, however, that during the pressing operation, the flanges arecontinuously reinforced by the mandrel of the present invention in sucha manner as to prevent distortion thereof. More particularly the flangesor chords of the channel are subj ected to the bracing influence of theworking surfaces of the blocks, that is, the tops and bases of theseveral blocks as each working surface during the pressing operation iscontacted by the flanges at successive points, as will be apparent.

In the use of ithe mandrel shown in Fig. 3, the same is inserted in thechannel as shown in said figure, the parts assuming the position clearlyillustrated. l/Vhen the channel is arranged between the dies and thelatter brought together to press the channel to the desired form, theblocks 18 will move vertically relative to each other during thepressing operation until the channel assumes the desired form. It can beseen-that during the pressing operation, the material of the channelwill always be in contact with the arcuate ends of the blocks 18'thereby bracing the channel against distortion. j For example, and toclearlyl show the operation of the blocks during the pressing of thechannel, certain of the blocks have been designated as 102, 103 and 104.Before the channel is bent, the blocks 102, 103 and 104 contact with theupper and lower chords of the channel in a manner and at points clearlyshown in Fig.

3, and the top o-f the block 104 extends beyond the non-contactingportion of the base of the adjacent block 102, and the top of block 102extends downwardly below the non-contacting portion of the base of block104. As can be seen in the drawings, the entire working surfaces of theseveral blocks 18 do not engage the chords of the channel for the reasonthat they are arcuate in shape, and due to the angular inclination ofthe several blocks, as before pointed out, the mandrel when inserted ina channel to be bent assumes the position shown in Fig. 3, with only aportion of the bases of the several blocks in engagement with theopposite chords of the channel; certain portions kof the bases beingshown in non-contacting relation with the chords. rlhe top of each block18 eX- tends beyond the non-contacting portion of the bases of theadjacent block, with the eX- ception of the two adjacent blocks arrangednext to the sizing head 28. This construction can be clearly seen whenthe blocks 102 and 104 are viewed. Now, upon pressing of the dies, theflanges of the channel will be bent upwardly around the bases'andtops ofthe sevmediate block. This will accord with the length of the finishedchannel, as will be apparent. -More particularly illustrating thisoperation, whenv the dies are brought together, to bend the channel tothe form shown in Fig. 1, the upper and lower flanges of the channelswill-be bent around the bases of the blocks 102 and 103 tending to forcethem downwardly, while at the same time thc lower flanges of the channelwill be bent around the base of the bloclr 104e urging the same upwardlyin a wedging manner between the straight sides of the blocks V102 and103, thereby separating the blocks 102 and 103 in an obvious manner. Theoperation just described is really a. series of successive steps,inasmuch as during the bending the block 103 is first acted upon, thentheblocl; 10a and finally the block 102, but the a-ctionis such that awedging of the several blocks results. Continuation of the pressing bythe dies causes the blocks to assume the position shown in Fig. 1; theblocks contacting with the channel flanges or chords, in the lastinstance, at points opposite the points shown in Fig. 3, and it will beapparent that those portions of the bases of the blocks which in thefirst instance were out of contact with the chords, are, at thecompletion of the pressing operation, in contact with the chords. Theblocks during the pressing operation shift successively verticallyrelative to each other; the operation being, in effect, a bending of thechannel, and more particularly the chords thereof, over the workingsurfaces of the blocks.

During the pressing of a channel in which the mandrel shown in Fig. 6 isemployed for reinforcing purposes, the several blocks of the saidmandrel shift vertically relative to each other and the several seriesforming the mandrel will shift horizontally relative to each other untilthey assume the position shown in Fig. 5. During the pressing operation,the series E will shift radially as well as laterally until the adjacentsurfaces of the blocks and 62, and 68 and 7 0 are arranged in abuttingrelation; in other words, with the mandrel shown in Fig. 6, the severalseries shift laterally with respect to each other, the blocks of eachseries shift vertically and laterally relative to each other, and theintermediate series of blocks E shift radially as a series, and theindividual blocks of said series E shift both laterally and verticallyrelative to each other. i f

It is believed `that the description and operation of the presentinvention Will be fullyv apparent to those skilled in the. art to whichit appertains, but itis to be understood that the drawings herein aremerely by Way of .example and that I `am not restricted to the specificform shown therein; it being apparent that various changes in the formand proportions of the device may be made Within the scope of theappended claims Without departing from the spirit of the invention.

Vhat is claimed is:

l. A flexible mandrel for insertion in a piece of Work to reinforce thelatter during bending comprising a plurality of blocks formed to provideWide Work contacting surfaces arranged in staggered relation Withrespect to each other, and meansiretaining the blocks in assembledposition at an angle inclined to a plane perpendicular to thelongitudinal axis of the mandrel, said blocks being shiftable relativeto each other during bending of the Work whereby the latter successivelycontacts With various points on ,the contacting surfaces.

2. A flexible. mandrel for insertion in a pieceof Work to reinforce'thelatter during bending comprising a plurality of blocks formed to provideWide and narrow Worlr contacting surfaces arranged in staggered relationWith respect to. each other, and means retaining the blocks in assembledposition at an angle inclined to a plane perpendicular to thelongitudinal axis of the mandrel, said blocks being shiftable relativetoeach other during bending ofthe Work whereby the latter successivelycontacts with various points on the contacting surfaces; f

3.'A flexible mandrel for insertion in a piece of Work to reinforce thelatter during bending comprisingV a plurality of blocks alternatelyarranged' to provide Wide Work contacting surfaces arranged in staggeredrelation with respect to each other, and means normally retaining theblocks in assembled relation at an angle inclined to a planeperpendicular to the longitudinal axis of the mandrel, 'said blocksbeing successively shiftable relative to each other'during bending ofthe Work. l

4C. A flexible mandrel forinsertion in a piece of Work to reinforce thelatter during bending comprising a plurality of blocks arranged toprovide'wide ivorl; contacting .surfaces arranged in staggered relationwith respect to each other, and means retaining the blocks in assembledrelation at an angle inclined to a plane perpendicular to the longitudinal axis of the mandrell said blocks being successively shiftablerelative to each other during bending of the Work wherebyV eachcontacting area provides a plurality of points with which'theWorlsuccessively contacts.

5.V In a flexible former, a plurality of blocks of triangular crosssectionI 'arranged to. preto present oppositely disposed Work Contact#ing areas arranged in staggered relation with respect to each other, a`flexible element on which the blocks are mounted, a sizing head at oneend of the flexible element and provided With an inner face againstWhich one side of one end block is adapted to rest Where' by the same ispositioned at an angle inclined to a plane perpendicular to thelongitudinal axis of the mandrel, a sizing head at the other end of theflexible element provided with an inclined inner face complementary tothe inclined side of the adjacent end block,

and means urging the last named sizing head into contact with theadjacent end block.V

7. A flexible mandrel forvinsertion in a channel to reinforce theflanges thereof dur-` ing bending, comprising a plurality of wedgeshapedblocks arranged to vpresent oppositely disposed Work contacting surfacesarranged in relation with respect to each ther and positioned at anangle inclined to a plane perpendicular to the longitudinal axis of themandrel, and means retaining said blocks in assembledposition, saidblocks being so mounted as to permit relative vertical and horizontalshifting thereof in the channel whereby some point of the Workingsurfaces thereof is in contact With channel flanges at all timesduringfthe bending, operation.

8. A flexible mandrel comprising end series of blocks arranged at anangle inclined to a plane perpendicular to the longitudinal axis of themandrel, an intermediate series of blocks inclined in a directionopposite the direction of inclination of the en'd series, and

means normally spacing said series 'of blocks, all of said blocks beingso formed as to be capable of relative shifting.

9. A flexible mandrel for insertion in a piece of Work to reinforce thelatter during bending comprising a plurality'of series of oppositelydisposed Wedge-shaped blocks arranged at an angle inclined to a lplane'perpendicular to'the longitudinal axis of the mandrel through the Work.

l0. In a flexible former', a plurality of blocks of triangular crosssection arranged to present a pluralityl of oppositely disposed :Widecontacting areas arranged in staggered relation With respect to eachother, and means for normally retaining said blocks `at an angleinclined to aplane perpendicular -tothe longi'- tudinal axis through themandrel.

ll. A -flexible mandrel comprising spaced'V series of inclined blocks',a series. of blocks.

los

intermediate the before mentioned spaced series and inclined in adirection opposite that of said spaced series, and means normallyretaining the several series of blocks in spaced relation.

12. A flexible mandrel comprising a plurality of Wedge shaped. blockshaving the larger ends thereof arranged adjacent the smaller ends of thenext successive blocks, a flexible element on Which said blocks aremounted, and means at the ends of said flexible element for retainingthe blocks in assembled relation and at an angle inclined to a planeperpendicular to the longitudinal axis through the mandrel.

In Witness whereof I have hereunto set my hand.

CHARLES F. WALP.

